A Conversation with Olaf Kirch

The author of the Linux Network Administrator's Guide tells us a little something about his life and the NAG.

Linux Journal: Tell us a little bit about yourself. How old
are you? Where did you go to school and what did you study? What
are your hobbies?

Olaf Kirch: I'm 28 and right
now I'm working as a developer for a small company in the CAD/CAM
business. I studied math and computer science at Darmstadt
University, Germany, and graduated about one year ago.

One of the things I do in my spare time is, of course, tend
Linux boxes, but I also read and paint a bit. And

I like bicycling. On my holidays, I love to go hiking with a
backpack—the farther away from any terminal, the better.

LJ: How did you start using
Linux?

Olaf: I installed my first
Linux system from an MCC Interim distribution some time back in
1992. Before that, my home box was an Atari running Minix, which
was a little painful. When I heard of Linux, I instantly junked the
Atari and bought a PC. I got the MCC release from some kind soul
who offered a gratis copying service on German Usenet. You only had
to send him seven floppies...

LJ: As the principal author
of the Linux Network Administrator's Guide, you have helped a lot
of Linux users. How did you get started?

Olaf: I got into the whole
project almost by accident. Initially, I meant to contribute only a
UUCP chapter to the System Administrator's Guide. When I followed
up with a chapter on smail and released it to the DOC channel on
Linux Activists, I mused aloud “Wouldn't it be nice to have an
entire Networking Guide?” “Hey, great,” everyone said, “I'd say, go
for it!” I was trapped.

Early on, progress was rather slow, because I wasn't as
comfortable with English as I thought. But the people on the DOC
channel were very helpful, and I got lots of reviews. My most
important reviewer was Andy Oram at O'Reilly, who got involved in
the book in late 1993.

Unfortunately, I also had to write my MS thesis, but in the
end it worked out well. I'm only glad my prof never caught me in
the terminal room.

LJ: You say you “trapped”
yourself into writing the NAG. Were you a networking guru when you
started writing it?

Olaf: No, not at all. I had
hacked on UUCP and various mailers like smail2 and umail, but my
ideas about TCP/IP networking, etc., were rather foggy. To put it
more bluntly, I was just another clueless newbie then. But I was
very curious, so I got myself some books, pestered developers with
stupid questions and spent endless hours browsing source code. BTW
(by the way), that's one of the main lessons I learned from the
whole thing: If you don't know how something works, read the
source. It really helps.

LJ: Do you have a network at
home or just a single computer?

Olaf: Most of the time, I
have only one computer at home, so I have to test a lot of things
using only local loopback. I do have some friends, however, who are
running networked Linux boxes and they always call me when they
have a problem or want to install new applications. This way I can
try out everything on their networks; this has the added benefit
that if anything goes wrong, their machines go down, not
mine.

LJ: What is your connection
to the Internet?

Olaf: I get mail and news
via UUCP from brewhq, our domain's main hub that has an Internet
uplink via ISDN. For interactive things like FTP, I use a SLIP
link, but I hope to have ISDN, too, some time soon.

LJ: What future do you see
for the NAG? Do you intend to keep revising it to keep it up to
date?

Olaf: Yes, I do, at least
for a while. The basic network administration issues in Linux don't
change that rapidly at the moment, so I think I'll release updates
every few months.

Of course, I'm aware there's a lot going on that I didn't
cover in the NAG, like IPX, ham radio and so on.

I also had offers from people who wanted to write something
on sendmail V8, INN and the BSD automounter. On the other hand, I
feel the book is already rather hefty, so

I'll probably not add any new sections. Maybe there will be a
sequel, but don't hold your breath.

Olaf: I'm thinking more of a
collection of papers, a little like the management documents in the
4.4BSD System Manager's Manual. I would want to make it less closed
than the NAG itself, so that different people can contribute more
easily. I had very firm ideas about how detailed the networking
guide should be, up to the point that some people considered it
“dumbed down”. Vince Skahan, who wrote the sendmail chapter never
complained, but I think I badgered him quite a lot. For the sequel,
I would lend people a hand at writing something, without imposing
my views on them.

LJ: What suggestions do you
have for those people who are interested in learning about topics
you decided not to cover? How can they learn about them?

Olaf: That depends. For some
packages, like INN, a quite exhaustive FAQ is distributed on the
Net. For sendmail V8, you can always get the bat book from
O'Reilly. It's about the size of a brick, but very useful. The IPX
and AX.25 stuff is still largely undocumented, so your best bet is
to read the sources.

LJ: What has Linux done for
your professional life?

Olaf: Difficult question.
People usually don't roll out the red carpet for you just because
you say, “Hey, I wrote a book on Linux, why don't you hire me?” On
my current job,

I don't get involved with network administration a lot. I'm
mainly coding C++ and Motif applications in an HP environment, but
I'm quite happy with it.

LJ: In the preface of the
NAG, you say that one of your favorite sports is “doing things with
sed that other people would reach for their perl interpreter for.”
Do you have a favorite sed hack you would like to tell us
about?

Olaf: First, let me say that
I don't believe perl is evil or anything. I just think that sed is
more fun, just the way the Obfuscated C Code Contest is. My
favorite sed hack is a short script I wrote that computes prime
numbers: If you give it a number n on standard input, it will print
all primes smaller than 2^n on standard out.

LJ: Will you give any hints
as to how you got that to work?

Olaf: There's nothing magic
about it. The script is a simple sieve algorithm. The only tricky
thing is incrementing and decrementing numbers. You can do that by
shifting a marker from right to left, very much like a carry flag.
Say I have 7890@ as input and want to decrement it. Then I replace
0@ with @9, and continue. Any other digit is decremented by one and
the marker removed, i.e., 9@ becomes 8, 8@ becomes 7, etc. Quite
silly, I admit.

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